Kinematics and Locomotion Analysis for the Six Legged Walking Robots Using the Theory of Screws, Reciprocal Screws and the Graph Theory

Abstract:

Not long time ago, legged walking robot, especially the robot that uses six legs to walk has received a great attention from researchers due to its extreme importance in several domains. Legged robots are suitable to function in an erratic, alarming and unsympathetic environments such as space habitat, mine territory, and benthos. Moreover, legged walking robots are satisfactory in some critical tasks like rescue applications and examine nuclear facilities. Generally, the legged robot divided in terms of the number of the legs into the two-legged, four-legged, six-legged and eight-legged robot. However, the six legs robot has asset over the first and the second one since the six-legged robot is much faster and stable. Furthermore, it has proven that increasing the legs of the robot will not give better results.
In this dissertation, an endeavor has exerted in order to handle the kinematic analysis of the walking robot that has six legs. A serial chain consists of three revolute joints (RRR) are chosen to form the leg of the robot due to reproducing the architecture of the insect’s leg. First, a brief summary of Denavit-Hartenberg (D-H) convention and the theory of screws, two of an essential technique used in the kinematic analysis of the robot manipulators, is provided. Then, the configurations of the walking robot’s leg studied in details for the sake of building a comprehensive representation of the six-legged walking robot. Third, the problem of finding the position and orientation of the center of gravity of the walking robot is solved using the closing circuit technique. In contrast, depending on knowing the pose of the center of mass of the robot, Inverse kinematics is achieved geometrically. Furthermore, screw theory approach has been beneficial to find the linear and angular velocity. However, the reciprocity theorem
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could deeply simplify the direct velocity analysis. Since the locomotion analysis is one of the most important aspects of walking robot, a review presented for the purpose of highlight on some fundamental locomotion approach. Finally, the mechanical configuration of the six-legged robot structures is to be represented using the theory of graph.
Keywords: Hexapod, Legged-Robot, Kinematics, D-H Convention, Screw Theory, Reciprocal Screws, Locomotion, Graph Theory.